System CallsIntroductionSteps in Making a System CallSome System Calls For Process ManagementSome System Calls For File ManagementSome System Calls For Directory ManagementSome System Calls For Miscellaneous TasksSystem Calls (5)Operating systemsOperating System StructureOperating System StructureSummarySystem CallsB.Ramamurthy (Adapted from Tannenbaum’s text)IntroductionSystem calls: The mechanism used by an application program to request service from the operating system. System calls often use a special machine code instruction which causes the processor to change mode (e.g. to "supervisor mode" or "protected mode"). This allows the OS to perform restricted actions such as accessing hardware devices or the memory management unit. From The Free Online Dictionary of Computing (http://foldoc.doc.ic.ac.uk/) is edited by Denis Howe <[email protected]>.Steps in Making a System Call There are 11 steps in making the system callread (fd, buffer, nbytes)Some System Calls For Process ManagementSome System Calls For File ManagementSome System Calls For Directory ManagementSome System Calls For Miscellaneous TasksSystem Calls (5)Some Win32 API callsOperating systemsThe OS may be split into a kernel which is always present and various system programs which use facilities provided by the kernel to perform higher-level house-keeping tasks, often acting as servers in a client-server relationship.Operating System Structure The client-server modelOperating System Structure The client-server model in a distributed systemSummaryWe studied the importance of system calls.And the structure of modern operating systems: client/server and
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